1. Field of the Invention
This invention relates to methods for increasing the sugar content of sugarcane and sorghum.
2. Prior Art
The primary purpose for growing sugarcane and sweet sorghum is the production of sugars, principally sucrose. All genetic improvements in crop varieties and innovations in fertilization, pest control and cultural practices are developed to produce highest yields of sugars per hectare with the least expenditure of energy and manpower. Additional ways to increase sugar yields are to induce the plant to either produce more sugars or to hold on to those already produced.
Vigorous vegetative growth uses up sugars because it requires high rates of metabolism. Squandering sugars by excessive growth near normal cane harvest time can be partially controlled by withholding water or by limiting nitrogen availability. These methods of ripening are not reliable because they are difficult to control. A more controllable, predictable method is to use specific chemical growth modifier sprays that will inhibit vegetative growth and allow sugars to build up in the stalks. Chemicals that will cause sucrose to accumulate are called cane ripeners or sugar enhancers.
During the past decade considerable research effort has been expended in the sugarcane industry to develop chemical sugar enhancers. N,N-bis-phosphonomethylglycine has emerged as a practical treatment in most cane growing areas of the world, particularly in high rainfall areas where natural ripening cannot be induced by withholding water. Newer experimental ripeners are being developed, which will have utility under wider rainfall conditions.
It has been estimated that about 5 million hectares of sugarcane are amenable to the application of chemical ripeners.
A wide variety of sulfonylurea compounds are known as broad spectrum herbicides and plant growth regulants. For example, U.S. Pat. Nos. 4,127,405, issued Nov. 28, 1978 and 4,169,719, issued Oct. 2, 1979, describe a number of triazine and pyrimidine compounds respectively for the above uses. Compounds useful in the present invention are described in published European Patent No. 7687, published on Feb. 6, 1980.